Titanium compounds, such as titanium nitride are finding increasing usage in a number of utilities, particularly in the production of electronic materials of construction for integrated circuits for computer chips.
Titanium nitride provides enhanced electrical conductivity for electronic circuits and exhibits excellent barrier properties for other metal depositions on silicon substrates. As a result, the electronics device fabrication industry has found increasing usage of titanium compound depositions for coatings prior to subsequent conductor metal depositions.
Techniques for titanium nitride deposition from tetrakis(dimethylamino)titanium (TDMAT) and tetrakis(diethylamino)titanium (TDEAT) are known in the literature. For instance, U.S. Pat. No. 5,139,825 discloses the deposition of titanium nitride from TDMAT or TDEAT in reaction with ammonia under chemical vapor deposition (CVD) conditions of 100 to 400° C., preferably 150 to 300° C., most preferably 200 to 250° C., under reduced pressure and using an inert carrier gas, such as nitrogen or helium, to deposit titanium nitride on a heated substrate, such as a heated silicon containing substrate.
However, the deposition rate of titanium nitride has been highly variable and does not lend itself to repeatable, precise use in the electronic fabrication industry, where a multitude of silicon wafers are processed simultaneously, and many batches of wafers are processed consecutively. High yields of electronically acceptable wafers are necessary for the titanium nitride process to be acceptable commercially to the electronics fabrication industry. Additionally, the speed of deposition is critical to provide economic processing of titanium nitride coated wafers in the hundred plus step processing of blank silicon wafers to the final electrically acceptable individual integrated circuits produced by the electronics fabrication industry.
The problems of low depostion rate and variable deposition rate for titanium compounds deposited by CVD from titanium containing precursors is unexpectedly overcome by the process of the present invention by the addtion of amine additives and/or the removal of trace amounts of hydrocarbon impurities as will be set forth with greater detail below.